DOUBLE WALL SHEET INCLUDING A PLASTIC SHEET HAVING A LARGE NUMBER OF RECESSED AND PROTRUDED PARTS AND METHOD TO PRODUCE IT

摘要

A plastic sheet having a number of recessed and protruded parts useful as a protective sheet in moving and construction, and for cushion packaging and thermal insulation is disclosed. Also disclosed is a two-layered or three-layered double wall sheet, which is produced by adhering one or two flat plastic sheets on the above plastic sheet. The double wall sheet has high rigidity against bending and improved warps when compared with the conventional plastic bubble boards, and is useful as the material for various panels and packaging containers. The plastic sheet is produced by vacuum forming to form plural protruded, truncated cone-shaped parts and recessed, ring-shaped parts surrounding and continuing from the protruding parts. The double wall sheet is produced by adhering a back sheet and/or liner sheet to the plastic sheet.